app/blueprints/thumbnails/__init__.py

   1 # Content DB
   2 # Copyright (C) 2018  rubenwardy
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
  16
  17
  18 from flask import abort, send_file, Blueprint, current_app
  19
  20 bp = Blueprint("thumbnails", __name__)
  21
  22 import os
  23 from PIL import Image
  24
  25 ALLOWED_RESOLUTIONS=[(100,67), (270,180), (350,233)]
  26
  27 def mkdir(path):
  28         assert path != "" and path is not None
  29         try:
  30                 if not os.path.isdir(path):
  31                         os.mkdir(path)
  32         except FileExistsError:
  33                 pass
  34
  35
  36 def resize_and_crop(img_path, modified_path, size):
  37         try:
  38                 img = Image.open(img_path)
  39         except FileNotFoundError:
  40                 abort(404)
  41
  42         # Get current and desired ratio for the images
  43         img_ratio = img.size[0] / float(img.size[1])
  44         ratio = size[0] / float(size[1])
  45
  46         # Is more portrait than target, scale and crop
  47         if ratio > img_ratio:
  48                 img = img.resize((int(size[0]), int(size[0] * img.size[1] / img.size[0])),
  49                                 Image.BICUBIC)
  50                 box = (0, (img.size[1] - size[1]) / 2, img.size[0], (img.size[1] + size[1]) / 2)
  51                 img = img.crop(box)
  52
  53         # Is more landscape than target, scale and crop
  54         elif ratio < img_ratio:
  55                 img = img.resize((int(size[1] * img.size[0] / img.size[1]), int(size[1])),
  56                                 Image.BICUBIC)
  57                 box = ((img.size[0] - size[0]) / 2, 0, (img.size[0] + size[0]) / 2, img.size[1])
  58                 img = img.crop(box)
  59
  60         # Is exactly the same ratio as target
  61         else:
  62                 img = img.resize(size, Image.BICUBIC)
  63
  64         img.save(modified_path)
  65
  66
  67 @bp.route("/thumbnails/<int:level>/<img>")
  68 def make_thumbnail(img, level):
  69         if level > len(ALLOWED_RESOLUTIONS) or level <= 0:
  70                 abort(403)
  71
  72         w, h = ALLOWED_RESOLUTIONS[level - 1]
  73
  74         upload_dir = current_app.config["UPLOAD_DIR"]
  75         thumbnail_dir = current_app.config["THUMBNAIL_DIR"]
  76         mkdir(thumbnail_dir)
  77
  78         output_dir = os.path.join(thumbnail_dir, str(level))
  79         mkdir(output_dir)
  80
  81         cache_filepath  = os.path.join(output_dir, img)
  82         source_filepath = os.path.join(upload_dir, img)
  83
  84         resize_and_crop(source_filepath, cache_filepath, (w, h))
  85         return send_file(cache_filepath)